Moving Progressively Away from the Ridges,the Ocean Water Depths Increase

Moving progressively away from the ridges,the ocean water depths increase systematically with seafloor age due to all but which of the following?

A) cooling and contraction of the oceanic crust with a resultant increase in density
B) isostatic down warping due to the weight of sediments deposited on the sea floor
C) erosion of the older ocean floor by deep ocean currents
D) conduction of heat away from the molten surface rocks